Means for coating webs



Oct. l', 1946', SBERGSTEIN xmms Foa comme wEs Find sept. 14. 1944 2 sheets-sheet 1 Illu.

cle-ooo* 'Sn/nuez. BERGSTEIN,

0tl, 1946. s. BERGsTElN 2,408,504

. mns Foa coA'rINGvwEBs Filed sept. 14, 1944 2 sheets-snip;

o I 2o 59mm. Benssreuv, I

INVENOR.

emplary embodiment.

` ls located close Patented Oct. 1, 1946 MEANS Fon coA'rING WEBS Samuel Bergstein, Cincinnati,

Ohio. assignor to A Robert Motrrie: Bergstein and Frank David Berg.

stein, trus Application September 14, 1944, Serial No. 554,022

to devices for applying lacquer or other coating web of paper or the My invention relates a continuous coating of materials to a continuous like.

It is an object of my invention to provide a mechanism whereby coatings containing solvents may be applied to the web without any material loss of the solvent during the actual coating op, Thus, the characteristics of a supply ofv eration. the coating material at the coating station is not subject to progressive changes due to solvent loss during the coating operation.

A further obiect of my invention is to provide an extremely simple and low cost coating mechanism which is adjustable' to a full range of webs within the width limit of the machine, which is readily adjustable to the coating of films of different thicknesses, and which provides a smooth, continuous coating on the web with a minimum of waste and Spoilage. l

A further object of my invention is the pro:` vision of means for coating which will prevent or minimize loss of the coating substance upon stoppage of the machine or breakage of the web.

These and other objects of my invention, which will b e set forth hereinafter or will be apparent to one skilled in lthe art upon reading this specification, I .accomplish by that certain construction and arrangement of parts and in that procedure of which I shall now describe an exv Reference is made to the drawings wherein:

Figure 1 is a diagrammatic pian view `of a mechanism according to my invention, the supply tank being shown in dottedlines, the cover being omitted.

Figure 2 is a diagrammatic sectional view of the mechanism shownin Figure 1. taken along the center line of that figure.

Figure 3 is a diagrammatic plan view of a now control means.

Figure 4 is a partial sectional view of the tank showing flow control means.

Figure 5 is a partial isometric view oi' the cover. Figure 6 is a partial isometric view of a side member showing adjustable means.

Briefly, in the practice of my invention, Iy cause a web to be coated to pass around the surface of a relatively large diameter cylinder or draw roll. tensioning the web as this is done so as to cause it to face of the cylinder without wrinkles or buckles. I carry the web away from the surface of the cylinder and beneath a knife or doctor which lie smoothly against the surgential path.

but spaced therefrom so that the web must fol.. low a short tangential tor blade. Side members are provided which en gage the surface of the web upon the cylinder, and are appropriately shaped to do this. The side members, however, have extensions, the lower edges of which follow the adjacent tan- They also have end portions closely approaching surfaces of the knife or doctor. The doctor and the side members together form with the web a reservoir in quantity of the coating substance may be maintained, the side members acting as dams for this reservoir and permitting both the use of lower viscosity materials and the maintenance of very much less volume in the reservoir than would be possible otherwise. v

In the drawings, to be coated is indicated at I, mounted upon a suitable shaft or mandrel 2, which in turn may be supported by a conventional back stand or unwinding stand. It should be understood that the unwinder may be va separate instrumentality or may be part of a single machine, as a matter of design. The unwinding device will be provided with a brake la to prevent overrunning and to tension the web.

It should be understood also that instead of rectly unwinding the web from a rolled suppLv and coating it as shown in the figures of this case, the web may proceed to my mechanism from sq volves in the direction of the arrow,

considerable portion to the surface of the cylinder is some other source oi' supply, such as al previous machine acting on the web, in which event precautions will be taken to restrain the web as aforesaid. so that it may be tensioned.

The web 3 passes around a break-over roll i on its way to a break-over roll may, if desired, be surfaced with rubber.

I prefer to drive the draw roll or cylinder l; and the provision of a variable speed drive, indicated at I8 between the roll 5 and a source of power 20, enables me at this point to control the speed of travel of the web 3 as it is being coated. such speed variation being .desirable in view of the nature oi' various coating substances in the production of coatings o: desired weights.

The break-over roll l is located closely adjacent to the draw roll 5. As the draw roll rethe web is caused to pass tightly around its surface for a of its circumference, thus causing the web to be smoothed out and freed of wrinkles. l

An adjustable blade or scraper 8 is suitably path in reaching the docwhich a. relatively small a'roll or supply of the web draw roll or cylinder 5. The

mounted in various ways as, for example, at its ends in side frames (not shown), of the machine Or it may be otherwise mounted on or in a member extending across between the side frames.

It is also made rotatably adjustable as to posi' tion. The working surface of the, doctor or knife ispreferabiy rounded, as shown inthe drawings, lso that itmay be adjusted to different angular relationships with the web, and means for angular adjustment are also provided. I have shown the knife or doctor 6 mounted on a shaft extending transversely across the machine. and provided with set screws; but other mountings and adjustment means may be employed. The angular relation of the knife to the web is one of the factors controlling thethickness of the applied coating.

After passing beneath the doctor or knife 6, the web 3 is drawn away at an agle tothe tangent and passes between upper and lower pinch rolls 1 and 8.

Adjustable, shaped side members 9 and l0 are provided. 'The under surfaces of these members have a portion i2 configured to conform to the surface of the web on the surface of the draw roll 5, and another portion I3 contoured to conform to the web in its short tangential travel be-l tween the surface of the draw roll 5 and the acting surface of the vknife or doctor B. The extreme ends of the side members are contoured, as

at it, to respond to the knife or doctor 6 in one position thereof. Where the knife or doctor must be adjusted to other rotative positions, other appropriately shaped side members may be substituted, or the side members 9 and I0 may be provided with adjustable extensions, indicated at i5, to permit them to be adjusted 'to various positions of the knife or doctor. These extensions may be plates, held to the `side member. by abolt ZI, and slotted as at 22 to permit appropriate adjustment.

The side members 9 and i0 may be so placed as to rest on extreme marginal portions of the web 3; and they serve as dams so that avery small quantity of the coating material may be continuously confined by the knife, the web, and

two side members.y Coating material is thus not.

lost off the edges of the web as in many coating operations, nor is it necessary to minimize this loss by maintaining a high viscosity in the coating material. The members 9 and l0 may be caused to rest at their proper positions by gravity,

wherefore, I have shown them slotted, as at I6,

the cross member il between the frames of the machine engaging in these slots. The members 9 and i0 are thus able to ride up and down as may be required for webs of different or differing thicknesses; but because it is a very short tangential path of travel for the web between the surface of the draw roll 5 and the line of contact of the doctor 6 with the web, the web is maintained in close engagement with the undersides of the members 9 and it) by the tension aforesaid.

The weight of the members 9 and' I 0 constitutes very little drag on the web. Since these elements overlie marginal edges of the web, these edges rev.main uncoated; but they may be later trimmed oilby knives or shearing means, as will be readily understood.

A tank Il for coating material is mounted above the surface of the draw roll. Thisv tank is tapered at its base, and the coating material in a con- 4 trolled stream flows out of the lower end of this tapered base through a narrow channel in the formof a slot or through a series of small, spaced orifices. Suitable means are provided for the regulation of flow of the coating material so as to deliver to the coating knife the proper quantity to replenish the supply of coating material thereat. The iiow will be regulated in accordance with the viscosity of the coating material and the speed of travel of the web.

The tank may be constructed and operated in a variety of ways. I prefer to provide an elongated tank which, as shown, extends across the width of the area to be coated, and is also equipped with a suitable cover to prevent undue evaporation of solvent. Such a tank may be provided at its base with a series of outlet perforations 23 (Figure 4) and also with a sliding plate Y 24, similarly perforated as at 25, and serving both as a means for opening and closing the perforations and asa means for regulating the volume of flow of the coating substance. For this purpose it may be provided at one end with an adjustabie stop 26 to control the open position and at the other end with a fixed stop 21 to determine a closed position. It may be spring-urged as at 28 to the closed position and moved to open position, if desired, by solenoid 29 or other means connected as by leads 30 to the circuit of the main drive for roll 5. Thus if the machine is stopped, the flow of coating substance from the tank will cease automatically.

My invention is particularly adapted to coating with lacquers or other substances in solution in volatile solvents. lExamples are: vinyl resins or other resins dissolved in acetone, alcohol, or similar solvents. The great bulk of the coating material is retained in a. tank so that it is not subject to loss o f solvent during the coating operation. as would be the case, for example, were the coating substance maintained in the conventional 'fountain and roller coating mechanism. When such mechanisms are employed with coating materials containing volatile solvents, there is a constant and large solvent loss which increases costs because. of the need for adding additional solvent from time to time. Solvent loss also makes the coating operation difficult because of progressive changes in the viscosity of the coating material as the solvent evaporates. In' my apparatus and process, a much better control of the coating is obtained because the quantity exposed under conditions where solvent eva-poration can occur is very greatly minimized, while the great bulk of the coating material is maintained in a closed tank where evaporation is minimized or prevented. It should be noted, however, that scraper blade to maintain the temperature of the coating substance, so long-as the web being coated is capable of withstanding the heats involved.

The adjustment of my mechanism, when changing from one width of web to another, is extremely simple and involves only the proper positioning of the side members so that they rest upon the marginal edges of the particular width of web being coated. Where it is desired to coat different parts of the same web with different :mossosl mediate the others and with suitable d ivisions4 in the tank I1 or suitable separate tanks as mal1 be desired, so that different coating materials may be applied to different areas ,of the web.

The coating material which flows from the tank l1 is delivered directly onto the web and is trapped in the pool aforesaid formed'by the-de# pression of the web itself between the blade and the draw roll with -the side members acting as dams. The amount of material held in this pool or reservoir at any given time is small, so that the coating operation may be caused to occur so rapidly that evaporation prior to coating is rendered immaterial. -The actual thickness or weight of the applied coating iscontrolled by the adjustment of the blade. The coating occurs uniformly across the face of the web. The amount of flow from the tank i1 is controlled,

. so that it is necessary only to start the machine.'

, been secured, the machine will continue inde- 1 nitely to apply a continuous film uniformly to the web.

As shown in. Figure l, the lower pinch roll 8 I is preferably a continuous cylinder contacting-the uncoated under side of the web. Instead of a continuous upper cylinder, I. may employ small friction discs 1, mounted upona shaft 1a, so that these vdiscs may be caused to contact the web on its uncoated marginal edges. The shaft 'ia may be driven by suitable means, such as a motor 3l,

at a slightly higher rate of speed than the speed of web travel, and continuously, i.e. they continue to rotate even though the main drive is idle.

make an adjustment, the tension rollers or discs 1 serve to maintain tension in the web so that,

whether moving or stationary, the web is at all times held in tension against the blade or doctor S. The maintenance of the coating material in the reservoir is thus assured. The use of the friction discs 1 instead of a. continuous roll pre- `vents any displacement of the coating by such Y a roll if the coating has nothardened 'or set by the time the web reaches elements 'l and 8.

After leaving elements 'I and 8, the web may ypass through a drying tunnel, it desired, and thereafter may be rewound or sheeted in the customary manner or may be conducted directly to other mechanisms to operate upon it, as for example, mechanisms i'or bag formation. Such `other mechanisms'form no limitation upon myinvention.

, From the above, it will be apparent that my invention provides a simple means for effectively supplying a, uniform coating to a web. No elabcrate doctor blades or coating rollers are required, the coating being done by a simple blade adjustable directly on the web. Except. for a minimum quantity reservoir oi the coating material on the 4 web itself, the coating materialis retained in a 6 9 and i0. The direction of tangential travel of the web from the draw roll 6 to the blade is preferably inclined downwardly, as shown; and the path is short, being at most several inches, so that there is no great area of unsupported web between the drawroll and the doctor blade.

with my apparatus, having depending side plates i8a, and being'supported on the side frames of the machine by extensions i8b in such a way as to cover the side members, the doctor bladev and the reservoir of material formed on the web. It will be slotted as at 82 to receive the nose of the tank. y

Modifications may be made in my invention without. departing from the spirit of it. Having thus described my invention in an exemplary embdiment, what I claim as new-and desire to se cure by Letters Patent is:

1. In a coating machine, a draw roll, a doctor blade having an operative edge located adjacent but spaced from the surface of said draw roll, means for moving a web under tension around a substantial circumferential portion of said draw roll and thence tangentially to the operating coating material ontol said web adjacent said doctor blade so as to cause said material to dam up against said doctor blade, and means for adweb by angular adjustment o! said doctor blade with respect to the tangential path of travel .of said blade.

2. In a coating'machine, la draw roll, a doctor'- blade having an operative 'edge located adjacent but spaced from the surface of said draw roll, means for moving a web under tension around a substantial circumferential portion of said draw roll and thence tangentially to the operating edge 404 of said doctor blade, means for introducing coating material onto said web adjacent said doctor blade soas to cause said material to dam up against said doctor blade, and means for adjusting the amount of coating appliedv to said web by angular adjustment oi said doctor blade with respect to thetangential path of travel of said blade, and means resting on the margins of said web and shaped to conform in part to the surface of said draw roll, in part to said tangential path oi' travel, and to a iace of said doctor blade. 5o 3. The structure claimed in claim -2 wherein the means for introducing the coated material onto said web includes an overhead tank with adjustable outlet means.

4. The structure claimed in claim 2 wherein the means for introducing the coating material onto said web includes an overhead tank with adjustable outlet means, said tank being closed except for `said outlet means whereby to minimize yevaporation of solvent from a coating sub- 30 stance. 5. The structure claimed in claim 2 wherein the means for introducing the coating material onto said web includes an overhead tank with adjustable outlet means, said tank being closed except for said outlet means whereby to minimize evaporation o! solvent from a coating substance, and having means to interrupt the flow o the coating material upon interruption of the `movement. of said web.

means resting on the margins ofsaid-web have attheir ends means adjustable to conform to the face oi said doctor blade in varyingpositions thereof.

A cover member i8 may be used in connection' edge of said doctor blade, means for introducing justing the amount of coating applied to said e. The strucmre claimed in ciaim 2 wherein 7. The structure claimed in claim 2 wherein said means resting on the margins of said web have at their ends means adjustable to conform to the face of said ldoctor blade in varying positions thereof, and wherein a cover member is provided enclosing said doctor blade, said members resting on the margins of said web as said web is being coated;

8. The structure claimed in claim 2 wherein said means resting on the margins of said web have at their ends means adjustable to conform to the face of said doctor blade in varying positions thereof, and wherein a cover member is provided enclosing said doctor blade, said members resting on the margins of said web as said web is being coated,said means for moving said web under tension comprising initial feeding means and retarding means therefor, and subsequent means for moving the web, said last mentioned means comprising a lower roll contacting an uncoated face of said web and upper coacting friction discs engaging uncoated marginal portions of sai( web.

9. The structure claimed in claim 2 wherein said means resting on the margins of said web have at their ends means adjustable to conform to the face of said doctor blade in varying positions thereof, and wherein a cover member is provided enclosing said doctor blade, said members resting on the margins oi' said web as said web is being coated, said means for moving said web under tension comprising initial feeding means and retarding means therefor, and subsequent means for moving the web. said means comprising a lower roll contacting an uncoated face of said web and upper coacting friction discs engaging uncosted marginal portions voi' said web, said frictionai discs being driven, and said draw roll being likewise driven.

; The structure claimed in`claim 2 wherein` said means resting on .the margins of said web have at their ends means adjustable to conform to the face of said doctor blade in varying positions thereof, and wherein a cover member is provided enclosing said doctor blade, said members resting on the margins of said web as said web is being coated, said means for moving said web under tension comprising initial feeding means and retarding means therefor. and subsequent means for moving the web, said means comprising a lower rollv contacting an uncoated face of said web and upper coacting friction discs engaging uncoated marginal portions of said web. said frictional discs being driven, and said draw roll being likewise driven, the drive for said friction discs being operative independently of the drive for said draw roll.

11. In a coating machine, means for applying braking resistance to a web, a break-over roll, an adjacent draw roll, a doctor blade near the surface of said draw roll but spaced therefrom and means for engaging and moving a web under tension, in the order named, said break-over roll acting to conduct said web to the surface of said draw roll, said draw roll being positioned with respect to said break-over roll and said doctor blade to cause the web to pass around a substantial portion of its surface, said draw roll and said engaging and moving means being located with respect to said doctor blade so as to cause said web to move tangentially to engage an edge of said doctor blade and then to move at an angle to the tangent toward said engaging and moving means, the said tangent being downwardly directed. and means for delivering coating material into the bight between said web and said doctor blade.

l2. The structure claimed in claim 11 wherein said engaging and moving means operate continuously at a peripheral speed slightly in excess of the speed of travel of said web.

13. The structure claimed in claim 11 wherein said engaging and moving means operate continuously at a peripheral speed slightly in excess oi' the speed of travel of said web, and wherein there are means engaging marginal portions of said web and resting thereon, said means conforming to said web on the surface of said draw roll, following said tangential path and conforminsr to a surface oi.' said doctor blade.

14. The structure claimed in claim 11 wherein said engaging and moving means operate continuously at a peripheral speed slightly in excess of the speed of travel of said web, and wherein there are means engaging marginal portions of said web and resting thereon. said means conforming to said web on the surface of said draw roll. following said tangential path and conforming to al surface of said doctor blade, and means for maintaining the positions of said last mentioned members in :the horizontal plane, while leaving said .members free for gravity actuated vertical movement.

SAMUEL BERGSTEIN. 

